This UV50 quarter zip base layer is designed to help regulate your body temperature, making it suitable for running, riding, or walking the dog. It features vented underarms to keep you cool and dry, and is sweat-wicking, anti-microbial, and offers 360-degree stretch for unrestricted comfort. The silky smooth fabric, ultra-soft seams, and flat lock stitches are designed to reduce chafing and minimize bulk when worn under other layers. Composition: 82% Nylon, 18% Elastane. Care: Machine washable up to 30 degrees.